Fair Value of Financial Instruments (Other Investments - Pacer) (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Other current assets	$ 58,234	$ 47,330
Pacer [Member] \| Investment [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Other current assets	$ 3,900	$ 2,900

Amount of current assets classified as other.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.8)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_OtherAssetsCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant